This invention relates to a method of rendering nonporous surfaces resistant to wetting and fogging.
When nonporous surfaces are relatively cool and are exposed to a warmer moist atmosphere, the cool surface has a tendency to become fogged. The accumulation of fog on the surface may be objectionable for several reasons. If the surface of the material is intended to be transparent, such as an automobile windshield or eyeglass lenses, fogging can become a danger as well as an inconvenience.
Because of the manner in which fogging occurs, it is important that any anti-foggant treatment adhere firmly to vertical surfaces to which it is applied for a substantial period and that it be initially clear and remain clear without collecting dust after application to the surface.
Numerous antifog formulations are disclosed in the literature. For example, in U.S. Pat. No. 4,615,738 there is disclosed a transparent antifog composition for nonporous substrates which comprises an aqueous solution of hexamethylcyclotrisiloxane, an aliphatic alcohol having up to 4 carbon atoms and a surfactant.
U.S. Pat. No. 3,620,820 discloses the application of silicofluorocarbon compounds to siliceous surfaces thereby rendering them resistant to wetting.
A glass cleaning composition consisting of 0.3 to 5 weight percent of a water soluble salt of an alkyl sulfate having from 10 to 16 carbon atoms, from 1 to 5 weight percent of a monomethyl or monoethyl ether of diethylene dipropylene glycols, from 5 to 15 weight percent of isopropanol and from 93.7 to 75 weight percent water is disclosed in U.S. Pat. No. 3,249,550. This patent describes the enhancement of the glass cleaning composition's antifogging properties by the incorporation therein of from 0.001 to 2 weight percent of a silicone glycol.